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# Swift Closure Challenge?

I am having trouble with this challenge. Here is the objective:

Given an array of integers, called numbers, use the filter function (and the helper function we created) to create a new array containing only odd numbers. Assign this new array to a constant named oddNumbers.

I am unsure of how to do this. There isn't another question for this challenge so there isn't really any help. Please help me. Here is my code:

filter.swift
```let numbers = [Int](0...50)

func isOdd(i: Int) -> Bool {
if i % 2 == 0 {
return false
} else {
return true
}
}

let numbers = [1,2,3,4,5]
let oddNumbers = numbers.map { isOdd }
```

First of all, `numbers` is initialized twice in you code. I'm pretty sure that the reason is that the challenge had already initialized the `numbers` array as:

```let numbers = [Int](0...50)
```

:and you didn't notice, which is why you wrote the declaration a second time.

The second reason this code isn't working is because you are trying to use closure expression to contain a function that already exists, while putting nothing in the curly braces which would make it a closure. Instead, replace the curly braces in the `.map()` function with parentheses:

```let oddNumbers = numbers.map(isOdd)
```

It is still not working??? What should i do?

Got it! You were using the wrong function altogether!

In the challenge description, it tells you to "use the filter function." That means it wants you to use the function called `filter()`, not `map()`.

It all has to do with the return type. Though both `filter()` and `map()` are capable of iterating through an array of type `Int`, `map()` is the one which, like the `isOdd` function, returns a Boolean value. Meanwhile, `map()` is used to replace each value with an updated one. The reason `map()` didn't work is because rather than using the returned `Bool` to decide whether or not to keep that item, it used the `Bool` as an item in the new array. `filter()` selects, `map()` replaces.

So recap; (1) initialize `numbers` only once; (2) parentheses instead of curly braces for the final function; and (3) use `filter()`, not `map()`.

Yes!!! Got it. Thanks for the help